'''
XMODEM Protocol bytes
=====================

.. data:: SOH

   Indicates a packet length of 128 (X/Y)

.. data:: STX

   Indicates a packet length of 1024 (X/Y)

.. data:: EOT

   End of transmission (X/Y)

.. data:: ACK

   Acknowledgement (X/Y)

.. data:: XON

   Enable out of band flow control (Z)

.. data:: XOFF

   Disable out of band flow control (Z)

.. data:: NAK

   Negative acknowledgement (X/Y)

.. data:: CAN

   Cancel (X/Y)

.. data:: CRC

   Cyclic redundancy check (X/Y)


ZMODEM Protocol bytes
=====================

.. data:: TIMEOUT

   Timeout or invalid data.

.. data:: ZPAD

   Pad character; frame begins

.. data:: ZDLE

   Escape sequence

.. data:: ZDLEE

   Escaped ``ZDLE``

.. data:: ZBIN, ZVBIN

   Binary frame indicator (using CRC16)

.. data:: ZHEX, ZVHEX

   Hex frame indicator (using CRC16)

.. data:: ZBIN32, ZVBIN32

   Binary frame indicator (using CRC32)

.. data:: ZBINR32, ZVBINR32

   Run length encoded binary frame (using CRC32)

.. data:: ZRESC

   Run length encoding flag or escape character


ZMODEM Frame types
==================

.. data:: ZRQINIT

   Request receive init (s->r)

.. data:: ZRINIT

   Receive init (r->s)

.. data:: ZSINIT

   Send init sequence (optional) (s->r)

.. data:: ZACK

   Ack to ZRQINIT ZRINIT or ZSINIT (s<->r)

.. data:: ZFILE

   File name (s->r)

.. data:: ZSKIP

   Skip this file (r->s)

.. data:: ZNAK

   Last packet was corrupted (?)

.. data:: ZABORT

   Abort batch transfers (?)

.. data:: ZFIN

   Finish session (s<->r)

.. data:: ZRPOS

   Resume data transmission here (r->s)

.. data:: ZDATA

   Data packet(s) follow (s->r)

.. data:: ZEOF

   End of file reached (s->r)

.. data:: ZFERR

   Fatal read or write error detected (?)

.. data:: ZCRC

   Request for file CRC and response (?)

.. data:: ZCHALLENGE

   Security challenge (r->s)

.. data:: ZCOMPL

   Request is complete (?)

.. data:: ZCAN

   Pseudo frame; other end cancelled session with 5* CAN

.. data:: ZFREECNT

   Request free bytes on file system (s->r)

.. data:: ZCOMMAND

   Issue command (s->r)

.. data:: ZSTDERR

   Output data to stderr (??)


ZMODEM ZDLE sequences
=====================

.. data:: ZCRCE

   CRC next, frame ends, header packet follows

.. data:: ZCRCG

   CRC next, frame continues nonstop

.. data:: ZCRCQ

   CRC next, frame continuous, ZACK expected

.. data:: ZCRCW

   CRC next, ZACK expected, end of frame

.. data:: ZRUB0

   Translate to rubout 0x7f

.. data:: ZRUB1

   Translate to rubout 0xff


ZMODEM receiver capability flags
================================

.. data:: CANFDX

   Receiver can send and receive true full duplex

.. data:: CANOVIO

   Receiver can receive data during disk I/O

.. data:: CANBRK

   Receiver can send a break signal

.. data:: CANCRY

   Receiver can decrypt

.. data:: CANLZW

   Receiver can uncompress

.. data:: CANFC32

   Receiver can use 32 bit Frame Check

.. data:: ESCCTL

   Receiver expects ctl chars to be escaped

.. data:: ESC8

   Receiver expects 8th bit to be escaped


ZMODEM ZRINIT frame
===================

.. data:: ZF0_CANFDX

   Receiver can send and receive true full duplex

.. data:: ZF0_CANOVIO

   Receiver can receive data during disk I/O

.. data:: ZF0_CANBRK

   Receiver can send a break signal

.. data:: ZF0_CANCRY

   Receiver can decrypt DONT USE

.. data:: ZF0_CANLZW

   Receiver can uncompress DONT USE

.. data:: ZF0_CANFC32

   Receiver can use 32 bit Frame Check

.. data:: ZF0_ESCCTL

   Receiver expects ctl chars to be escaped

.. data:: ZF0_ESC8

   Receiver expects 8th bit to be escaped

.. data:: ZF1_CANVHDR

   Variable headers OK

ZMODEM ZSINIT frame
===================

.. data:: ZF0_TESCCTL

   Transmitter expects ctl chars to be escaped

.. data:: ZF0_TESC8

   Transmitter expects 8th bit to be escaped

'''

SOH = b'\x01'
STX = b'\x02'
EOT = b'\x04'
ACK = b'\x06'
XON = b'\x11'
XOFF = b'\x13'
NAK = b'\x15'
CAN = b'\x18'
CRC = b'\x43'

TIMEOUT = None
ZPAD = 0x2a
ZDLE = 0x18
ZDLEE = 0x58
ZBIN = 0x41
ZHEX = 0x42
ZBIN32 = 0x43
ZBINR32 = 0x44
ZVBIN = 0x61
ZVHEX = 0x62
ZVBIN32 = 0x63
ZVBINR32 = 0x64
ZRESC = 0x7e

# ZMODEM Frame types
ZRQINIT = 0x00
ZRINIT = 0x01
ZSINIT = 0x02
ZACK = 0x03
ZFILE = 0x04
ZSKIP = 0x05
ZNAK = 0x06
ZABORT = 0x07
ZFIN = 0x08
ZRPOS = 0x09
ZDATA = 0x0a
ZEOF = 0x0b
ZFERR = 0x0c
ZCRC = 0x0d
ZCHALLENGE = 0x0e
ZCOMPL = 0x0f
ZCAN = 0x10
ZFREECNT = 0x11
ZCOMMAND = 0x12
ZSTDERR = 0x13

# ZMODEM ZDLE sequences
ZCRCE = 0x68
ZCRCG = 0x69
ZCRCQ = 0x6a
ZCRCW = 0x6b
ZRUB0 = 0x6c
ZRUB1 = 0x6d

# ZMODEM Receiver capability flags
CANFDX = 0x01
CANOVIO = 0x02
CANBRK = 0x04
CANCRY = 0x08
CANLZW = 0x10
CANFC32 = 0x20
ESCCTL = 0x40
ESC8 = 0x80

# ZMODEM ZRINIT frame
ZF0_CANFDX = 0x01
ZF0_CANOVIO = 0x02
ZF0_CANBRK = 0x04
ZF0_CANCRY = 0x08
ZF0_CANLZW = 0x10
ZF0_CANFC32 = 0x20
ZF0_ESCCTL = 0x40
ZF0_ESC8 = 0x80
ZF1_CANVHDR = 0x01

# ZMODEM ZSINIT frame
ZF0_TESCCTL = 0x40
ZF0_TESC8 = 0x80

# ZMODEM Byte positions within header array
ZF0, ZF1, ZF2, ZF3 = range(4, 0, -1)
ZP0, ZP1, ZP2, ZP3 = range(1, 5)

# ZMODEM Frame contents
ENDOFFRAME = 2
FRAMEOK = 1
TIMEOUT = -1      # Rx routine did not receive a character within timeout
INVHDR = -2       # Invalid header received; but within timeout
INVDATA = -3      # Invalid data subpacket received
ZDLEESC = 0x8000  # One of ZCRCE/ZCRCG/ZCRCQ/ZCRCW was ZDLE escaped

# MODEM Protocol types
PROTOCOL_XMODEM = 0x00
PROTOCOL_XMODEMCRC = 0x01
PROTOCOL_XMODEM1K = 0x02
PROTOCOL_YMODEM = 0x03
PROTOCOL_ZMODEM = 0x04

PACKET_SIZE = {
    PROTOCOL_XMODEM: 128,
    PROTOCOL_XMODEMCRC: 128,
    PROTOCOL_XMODEM1K: 1024,
    PROTOCOL_YMODEM: 1024,
    PROTOCOL_ZMODEM: 1024,
}

# CRC tab calculated by Mark G. Mendel, Network Systems Corporation
CRC16_MAP = [
    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
    0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
    0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
    0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
    0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
    0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
    0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
    0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
    0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
    0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
    0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
    0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
    0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
    0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
    0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
    0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
    0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
    0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
    0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
    0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
    0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
    0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
    0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
    0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
    0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
    0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
    0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
    0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
    0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
    0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
    0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
    0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0,
]

# CRC tab calculated by Gary S. Brown
CRC32_MAP = [
    0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
    0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
    0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
    0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
    0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
    0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
    0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
    0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
    0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
    0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
    0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
    0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
    0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
    0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
    0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
    0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
    0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
    0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
    0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
    0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
    0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
    0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
    0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
    0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
    0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
    0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
    0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
    0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
    0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
    0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
    0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
    0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
    0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
    0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
    0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
    0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
    0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
    0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
    0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
    0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
    0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
    0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
    0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
]
